About this world
HD 156668 b is a super-Earth orbiting HD 156668, an orange dwarf (type K2) 79.4 light-years from Earth. It is about 1.9 times the size of Earth (its size estimated from its mass), with at least 4.2 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 4.65 days at 0.05 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 887 K (614 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock.
It was discovered in 2010 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 156668 has 2 known planets; the others are HD 156668 c.